Device for reducing contact pressure of a bobbin contacting a drive drum of a thread winding arrangement

ABSTRACT

There is disclosed a device for reducing the contact pressure of a bobbin contacting a drive drum of a winding arrangement for threads or the like. The inventive device comprises a machine frame, a pivotable bobbin support arm and loading spring means cooperating with said bobbin support arm for providing the bobbin contact pressure. A lever is pivotably arranged on the machine frame and a guide element determines the position of said lever. According to an important aspect of the invention, the loading spring means is attached to the bobbin support arm in the vicinity of the bobbin and is hinged to the machine frame via the aforesaid lever, so that the guide element of the bobbin support arm deflects this lever and the loading spring means over a certain distance while the bobbin support arm is tilted.

O United States Patent [151 3,661,334 Graf May 9, 1972 [54] DEVICE FOR REDUCING CONTACT 3,430,875 3/1969 Kieronski ..242/18 DD PRESSURE OF A BOBBIN CONTACTING A DRIVE DRUM OF A FOREIGN PATENTS OR APPLICATIONS THREAD WINDING ARRANGENIENT 770,474 7/1934 France ..242/18 DD 530,856 12/1940 Great Britain ..242/18 DD 1 lnvemofl Felix Winteflhur, Swnzerland 898,038 6/1962 Great Britain ..242/18 DD [73] Assignee: Rieter Machine Works Ltd., Winterthur,

Switzerland Przmary Examiner-Stanley N. Gilreath Att0rne vWerner W. Kleeman [22] Filed: Oct. 14, 1969 2| 1 Appl. No.2 866,346 1571 ABSTRACT There is disclosed a device for reducing the contact pressure [30 I Foreign Appncmion p Dam of a bobbin contacting a drive drum of a winding arrangement for threads or the like. The inventive device comprises a 0C1. 21, 1968 swllzerland ..l5742/68 machine frame a pivotable bobbin support arm and loading 7 Y spring means cooperating with said bobbin support arm for [5-] LS. Cl.. ..242/18 DD providing the bobbin Contact pressure A lever is pivombly an [5 l l '3" Cl B65h 54/42 ranged on the machine frame and a guide element determines [58] Field of Search ..242/18 DD, 65 the position of said ever. According m an important aspect of the invention, the loading spring means is attached to the bob- [56] References cued bin support arm in the vicinity of the bobbin and is hinged to UNITED STATES PATENTS the machine frame via the aforesaid lever, so that the guide element of the bobbin support arm deflects this lever and the 2,753,125 7/1956 Wurmlt ..242/18 DD loading spring means over a certain distance while the bobbin 2,957,635 10/1960 Bisbe..... ....242/18 DD Suppon arm is mtecL 3,009,661 11/1961 Akers ....242/18 DD 3,363,850 1/1968 Lingerfelt ..242/18 DD 9 Claims, 4 Drawing Figures DEVICE FOR REDUCING CONTACT PRESSURE OF A BOBBIN CONTACTING A DRIVE DRUM OF A THREAD WINDING ARRANGEMENT BACKGROUND OF THE INVENTION The present invention broadly deals with textile apparatus and, more specifically, relates to an improved device or apparatus for reducing the contact pressure of a bobbin contacting a drive drum of a thread winding arrangement such as used, for example, on take-up, draw-winding and spin-drawwinding machines.

The textile art is already well acquainted with the use of spring loading for pressing bobbins rotatably supported by a pivotable arm against a drive drum in order to maintain the circumferential speed of the frictionally driven bobbin constant, independent of the increase in the diameter of the thread or yarn package. In these prior art winding arrangements, it is known to influence, through the action of an adjustable spring, the contacting pressure of bobbins by means of a guide roll arranged on the arm and a lever pivotably arranged on the machine frame. However, this arrangement was primarily aimed at cancelling out the influence of the weight of the package, which increases during package formation, by suitably choosing the guide curve or cam of the lever guiding the roll, in order to maintain the contacting pressure as uniform as possible. But, it has been found that maintenance of the contacting pressure as uniform as possible is indeed disadvantageous, because initially a certain contact pressure is necessary in order to avoid slippage, yet such pressure is no longer required in the later phases of the package build or formation and even causes squeezing of the thread layers laterally out of the package.

Furthermore, bobbin support arms are known to the art in which helical springs are axially arranged on the bobbin pivoting shaft in order to generate the contact pressure Here, the influence of the springs is suppressed during such time as the bobbin is in its so-called idle position, (i.e., in the bobbin change or exchange position) by means of a ratchet device. In this arrangement, one end of the spring has been inserted into the support arm and the other end into the machine frame. These arrangements exhibit the drawback that spring characteristics alone are responsible for the magnitude of the contacting pressure, which can only be changed or adapted by exchanging the spring. Yet, the exchange or replacement of helical springs arranged in the manner heretofore described, is very time-consuming, wherefore practical reasons hardly render such solution worthy of consideration.

Continuing, it should be appreciated that the prior art has also contemplated systems in which combinations of weights and springs serve to generate the contacting pressure. Now, in

order to arrange these weights, it was necessary to provide additional levers which were disposed at an angle to the bobbin support arm and on which the weights could then be displaced and adjusted. Yet, it has been found that this physical construction possesses the drawback that, inasmuch as the action of the weights depends upon the distance from the pivot point and the location of the weight supporting levers, their torsional moment or moment of rotation transmitted to the bobbin support arm again is determined by the position of the weights. Although a given or predetermined characteristic of contact pressure can be approximated to some extent by using this combination of springs and weights, still sufficient precision cannot be achieved. Moreover, the arrangement of weights upon levers interferes with the attainment of a compact design of the machine.

SUMMARY OF THE INVENTION Accordingly, it is a primary objective of the present invention to provide an improved device for reducing the contact pressure of a bobbin contacting a drive drum of a thread winding machine, and specifically, wherein such device overcomes the aforementioned drawbacks of the prior art constructions.

Another, more specific object of the present invention relates to the provision of an improved device of the aforementioned type which utilizes simple means and provides for a fast initial drop in the contact pressure and subsequently an almost constant contact pressure.

Still a further object of the present invention relates to an improved device for reducing the contact pressure of a bobbin contacting a drive drum of a winding arrangement for threads or the like, wherein such contacting pressure is adaptable to the requirements of the respective processing conditions by means of easily exchangeable elements.

Yet, a further, important object of the present invention re lates to the provision of an improved device for the reduction of the contact pressure of a bobbin contacting the drive drum of a thread winding arrangement possessing a design which is as compact as possible.

Now, in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the invention contemplates the provision of an improved device for the reduction of the contact pressure of a bobbin contacting a drive drum of a winding arrangement for threads or the like, which is of the type incorporating a pivotable bobbin support arm and loading spring means providing the bobbin contact pressure. There is also provided a guide element for determining the position of a lever pivotably arranged on the machine frame. According to an important aspect of the invention, the loading spring means is attached to the bobbin support arm in the vicinity of the bobbin and is hinged to the machine frame via the lever, so that the guide element of the bobbin support arm deflects such lever and the loaded spring means through a certain distance when the bobbin support arm is tilted.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood, and objects other than those set forth above, will become apparent, when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein:

FIG. 1 is a'schematic elevational view of a preferred embodiment of inventive winding arrangement at the beginning of the package build or formation;

FIG. 2 is a view similar to the winding arrangement of FIG. 1, but showing the arrangement of the components at the end of the winding operation;

FIG. 3 depicts the winding arrangement of FIG. I in a position wherein the bobbin support arm is completely tilted out into its bobbin change or exchange position; and,

FIG. 4 is a graph plotting bobbin contact pressure as a function of package diameter, such bobbin contact pressure being plotted along the ordinate and the package diameter along the abscissa of such graph.

DETAILED DESCRIPTION OF THE PREFERRED INVENTIVE EMBODIMENT Describing now the drawings, it will be seen that a thread 1 consisting of one or more endless filaments, is transferred through the action of a traversing thread guide element 2 onto a bobbin 5, the traversing thread guide element 2 being guided by a grooved drum 4 supported in the machine frame 3. Bobbin 5 is rotatably supported by a pivotably mounted bobbin support arm 6 and is frictionally driven through contacting a friction drive drum 7 arranged at the machine frame 3. As a result, thread 1 or the like is wound-or taken-up in layers at a constant speed upon the bobbin 5. The contact or contacting pressure of the bobbin 5 upon the drive drum 7, which is required for this purpose, is provided by means of a tension spring 8. This tension spring 8 has its upper end hingedly or pivotably connected, at location A, to the bobbin support arm, and similarly its lower end is hingedly connected, at location B, to a lever 9. This lever 9 is mounted at the machine frame 3 and pivots in a plane parallel to the plane of pivoting of the bobbin support arm 6. The pivot axis C of the lever 9 is arranged at approximately the same height as the pivot axis or location D of the bobbin support arm 6, but is located somewhat farther to the inside, as shown.

Furthermore, it will be recognized that on the lower half of the bobbin support arm 6, there is arranged a roll or roller member 10 which cooperates or works in concert with a guide curve or cam 11, also sometimes referred to as cam surface, provided at the lever 9. Additionally, the bobbin support arm 6 is provided with a projection or protruding arm portion 12 which is directed downwards, and the end of which rests against a suitable stop member 13 provided at the machine frame 3 when the bobbin support arm 6 is tilted out fully into its bobbin change position. Additionally, a damping device 14 is hinged to the projecting arm portion or projection 12 for the purpose of damping vibrations caused by out-of-round bobbins or tubes. This device also serves to protect the bobbin support bearings, as otherwise the still empty bobbin would .contact the drive drum 7 with a hard impact when the bobbin support arm is tilted back.

As clearly indicated in FIG. 1, the hinge or pivot points A and B of spring member 8 and the hinge point C of the lever 9 are located on a straight line g when the empty bobbin 5 contacts the drive drum 7. Moreover, the distance of the guide curve or cam 11 of the lever 9 from the roll 10 arranged on the bobbin support arm 6 is chosen such that no deflection of the spring pivot points, out of this straight line, is efiected in this position. Now, as best observed by referring to FlG. 2, as the diameter d of the bobbin 5 gradually increases owing to the formation or build of the package, then the bobbin support arm 6 slowly pivots in counterclockwise direction, the roll 10 contacts the guide curve or cam 11, the lever 9 is deflected from the straight connection line g and the spring member 8 is additionally tensioned. Above all, however, the moment determined by the product of the spring force P and the lever arm length a, acting on the bobbin support arm 6, is increased. Continuing, the distances between the guide roll 10 and the guide curve or cam 11 are chosen such that the action of the spring force increases as the bobbin support arm 6 swings through its vertical position, by virtue of which arrangement the component of the force tilting this bobbin support arm 6 counterclockwise and generated by the increasing package weight is over-compensated as tilting continues. Through suitable selection of the guide curve or cam surface 11, it is possible, after the arm 6 has passed its vertical position, to achieve an initial pronounced or sharp drop in the contact pressure and, subsequently, an approximately constant contact pressure, as best evidenced by referring to the graph of F IG. 4. The contact pressure present between the bobbin and drive drum must be relatively high at the initial stages of package build-up to counteract any possible danger of slippage of the empty bobbin on the drive drum. This danger is progressively reduced as the thread package builds-up at the bobbin so that when, for instance, the bobbin support arm has been pivoted into its vertical position, in other words has moved through a predetermined initial angle of tilt or pivotal movement between its starting position when the bobbin is empty and such vertical position, sufficient thread has now been wound onto the bobbin to ensure against slippage and thus, thereafter, the previously prevailing higher contact pressure may drop quite sharply. Thereafter, the contact pressure is maintained approximately constant at a reduced level throughout formation of the package, so that the undesirable lateral squeezing out of thread layers is suppressed.

Hence from what has been explained above it should be understood that during such time as the diameter of the bobbin 5 gradually increases owing to thread package build-up thereon the bobbin support arm 6 slowly pivots in counterclockwise direction from its starting position, as shown in FIG. 1 where the empty bobbin contacts the drive drum 7, towards the vertical position of the bobbin support arm. During such time the moment exerted by the force of the spring member 8 is positive, that is, tends to increase as the bobbin support arm 6 swings into its vertical position. Now, after the bobbin support arm 6 moves through the vertical position, in other words when this bobbin support arm 6 is inclined towards the outside, then the weight of the bobbin has a negative effect or negative moment which counteracts the moment produced by the spring. This in efiect results in a reduction i.e., an initial pronounced or sharp drop in the contact pressure. In other words, before the bobbin support am has reached its vertical position, the moment which is exerted by the spring member is assisted by the weight of the thread package, but after the bobbin support ann has moved through such vertical position the package weight counteracts the moment of the spring, resulting in the previously explained reduction in the contact pressure.

It is to be understood that the guide curve 11 arranged on the lever 9 extends upwardly, vertically at first (FIG. 1), and then follows a quadrant or quarter circle path 16. The end point of the quadrant 16 is arranged approximately at right angles to its starting point. As best recognized by referring to FIG. 3, the lever 9 is also provided with a projection means or guide curve zone 17 which, when the bobbin support arm 6 is tilted out fully, as shown, extends approximately parallel to this bobbin support ann 6 and permits tilting of such arm 6 over a neutral or dead-center position T. Thus, the bobbin support arm 6, even if unloaded, that is, after doffing the full package, cannot tilt back by itselfany longer.

It should be apparent from the foregoing detailed description, that the objects set forth at the outset to the specification have been successfully achieved. Accordingly,

lclaim:

l. A device for reducing the contact pressure of a bobbin having a bobbin axis and which contacts a drive drum of a winding arrangement for threads or the like wound into a thread package on the bobbin, comprising a pivotable bobbin support arm, means for mounting said bobbin support arm for pivotal movement from a starting position where the empty bobbin contacts the drive drum through a vertical position as the thread package progressively builds-up on the bobbin and into a fully tilted-out bobbin-change position where the bobbin is out of contact with the drive drum, loading spring means cooperating with said pivotable bobbin support arm for providing the bobbin contact pressure, a machine frame, a lever pivotably attached at said machine frame, said lever being provided with a cam surface, a guide element provided for said bobbin support arm engageable with said cam surface for determining the position of said lever, said spring means being attached at one end to said bobbin support arm at the vicinity of the bobbin axis and at its other end to said machine frame through the agency of said lever, so that said guide element of said bobbin support arm deflects said lever along its cam surface together with said spring means through a certain distance when the bobbin support arm is pivoted, the weight of the thread package initially urging the bobbin support arm against the drive drum as the bobbin support arm moves from said starting position towards said vertical position whereas upon passing through said vertical position the weight of the thread package urges said bobbin support arm away from the drive drum.

2. A device as defined in claim I, wherein the pivot point of said lever is located in the vicinity of the pivot axis of said bobbin support arm between the latter and the machine frame.

3. A device as defined in claim 1, wherein the points of attachment of said spring means and said lever are located along a straight line when said bobbin support arm is in its starting position.

4. A device as defined in claim 1, wherein said cam surface is designed such that it deflects said lever and spring means when said bobbin support arm moves through said vertical position.

5. A device as defined in claim 1, wherein said cam surface defines a quadrant of a circle which at its lower end is directed upwardly in the direction of said bobbin support arm and then at its upper end is directed laterally towards said bobbin support arm.

6. A device as defined in claim 5, wherein said lever is provided with projection means at the end of said quadrant of a circle, said projection means extending approximately in the direction of said bobbin support arm when the latter is tilted out fully into a bobbin change position.

7. A device as defined in claim 6, wherein said projection means at the end of said quadrant of a circle prevents said bobbin support arm when in its bobbin change position from tilting back by itself after said guide element has moved into contact with said projection means.

8. A device as defined in claim 1, further including damping means to which said bobbin support arm is connected.

9. A device for reducing the contact pressure of abobbin having a bobbin axis and which contacts a drive drum of a winding arrangement for threads or the like wound into a thread package on the bobbin, comprising a pivotable bobbin support arm, means for mounting said bobbin support arm for pivotal movement from a starting position where the empty bobbin contacts the drive drum through a vertical position as the thread package progressively builds-up on the bobbin and into a fully tilted-out bobbin-change position where the bob- 6 bin is out of contact with the drive drum, loading spring means cooperating with said pivotable bobbin support arm for providing the bobbin contact pressure, a machine frame, a lever pivotablylarranged at said machine frame, said lever being provided with a cam surface, a guide element carried by said bobbin support arm and engageable with said cam surface for determining the position of said lever, said spring means being attached at one end to said bobbin support arm at the vicinity of the bobbin axis and at its other end to said machine frame through the agency of said lever, so that said guide element deflects said lever along its cam surface together with said spring means when said bobbin support arm has moved through a predetermined angle of pivotal movement, the weight of the thread package initially urging the bobbin support am against the drive drum as the bobbin support arm moves from said starting position towards said vertical position whereas upon passing through said vertical position the weight of the thread package urges said bobbin support arm away from the drive drum.

* i II i 

1. A device for reducing the contact pressure of a bobbin having a bobbin axis and which contacts a drive drum of a winding arrangement for threads or the like wound into a thread package on the bobbin, comprising a pivotable bobbin support arm, means for mounting said bobbin support arm for pivotal movement from a starting position where the empty bobbin contacts the drive drum through a vertical position as the thread package progressively builds-up on the bobbin and into a fully tilted-out bobbin-change position where the bobbin is out of contact with the drive drum, loading spring Means cooperating with said pivotable bobbin support arm for providing the bobbin contact pressure, a machine frame, a lever pivotably attached at said machine frame, said lever being provided with a cam surface, a guide element provided for said bobbin support arm engageable with said cam surface for determining the position of said lever, said spring means being attached at one end to said bobbin support arm at the vicinity of the bobbin axis and at its other end to said machine frame through the agency of said lever, so that said guide element of said bobbin support arm deflects said lever along its cam surface together with said spring means through a certain distance when the bobbin support arm is pivoted, the weight of the thread package initially urging the bobbin support arm against the drive drum as the bobbin support arm moves from said starting position towards said vertical position whereas upon passing through said vertical position the weight of the thread package urges said bobbin support arm away from the drive drum.
 2. A device as defined in claim 1, wherein the pivot point of said lever is located in the vicinity of the pivot axis of said bobbin support arm between the latter and the machine frame.
 3. A device as defined in claim 1, wherein the points of attachment of said spring means and said lever are located along a straight line when said bobbin support arm is in its starting position.
 4. A device as defined in claim 1, wherein said cam surface is designed such that it deflects said lever and spring means when said bobbin support arm moves through said vertical position.
 5. A device as defined in claim 1, wherein said cam surface defines a quadrant of a circle which at its lower end is directed upwardly in the direction of said bobbin support arm and then at its upper end is directed laterally towards said bobbin support arm.
 6. A device as defined in claim 5, wherein said lever is provided with projection means at the end of said quadrant of a circle, said projection means extending approximately in the direction of said bobbin support arm when the latter is tilted out fully into a bobbin change position.
 7. A device as defined in claim 6, wherein said projection means at the end of said quadrant of a circle prevents said bobbin support arm when in its bobbin change position from tilting back by itself after said guide element has moved into contact with said projection means.
 8. A device as defined in claim 1, further including damping means to which said bobbin support arm is connected.
 9. A device for reducing the contact pressure of a bobbin having a bobbin axis and which contacts a drive drum of a winding arrangement for threads or the like wound into a thread package on the bobbin, comprising a pivotable bobbin support arm, means for mounting said bobbin support arm for pivotal movement from a starting position where the empty bobbin contacts the drive drum through a vertical position as the thread package progressively builds-up on the bobbin and into a fully tilted-out bobbin-change position where the bobbin is out of contact with the drive drum, loading spring means cooperating with said pivotable bobbin support arm for providing the bobbin contact pressure, a machine frame, a lever pivotably arranged at said machine frame, said lever being provided with a cam surface, a guide element carried by said bobbin support arm and engageable with said cam surface for determining the position of said lever, said spring means being attached at one end to said bobbin support arm at the vicinity of the bobbin axis and at its other end to said machine frame through the agency of said lever, so that said guide element deflects said lever along its cam surface together with said spring means when said bobbin support arm has moved through a predetermined angle of pivotal movement, the weight of the thread package initially urging the bobbin support arm against the drive drum as the bobbin support arm moves from said starTing position towards said vertical position whereas upon passing through said vertical position the weight of the thread package urges said bobbin support arm away from the drive drum. 